(a) Field of the Invention
The present invention relates to a node apparatus, a method of receiving an optical signal thereof, and a ring network system.
(b) Description of the Related Art
As a network that can provide more bandwidth is required according to an increase in the number of Internet users and a wideband multimedia service, in an optical communication system, optical fiber is used as a transmission medium, and a wavelength division multiplexing (WDM) method is used.
The WDM method multiplexes and transmits optical signals of different wavelengths to one optical fiber.
Particularly, in an optical communication system of a WDM method having a ring structure, node apparatuses are connected in a ring form. In an optical communication system of a WDM method having such a ring structure, because data that are transmitted from one node are transmitted in one direction along a ring, a node apparatus rather than a destination to receive data reproduces an optical signal as needed, and transmits the optical signal to the next node apparatus. That is, in order to receive a signal that is received in one node apparatus in another node apparatus, a signal should be reproduced and retransmitted. Thereby, in each node apparatus, the quantity of receivers should be equal to that of optical wavelengths in the node apparatus, and in each node apparatus, the quantity of transmitters should also be equal to that of optical wavelengths that receive in the node apparatus, and thus in each node apparatus transmitters corresponding to the quantity of optical wavelengths are required.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.